Polarizers are used in a variety of applications such as liquid crystal displays, three-dimensional displays, medical imaging, polarimetry, and interferometry. A polarizer is an optical device that transmits light of one polarization and blocks or absorbs light of different polarizations. A polarizer can be fabricated to transmit linearly, circularly, or elliptically polarized light. Linear polarizers can be fabricated by exploiting the optical properties of birefringence or dichroism. For example, etched dichroic polymers and wire-grid polarizers are existing conventional techniques well-suited for fabricating linear polarizers. However, circular and elliptical polarization elements are more difficult to construct.
Liquid crystal materials may exhibit desirable optical properties, such as birefringence, when molecules of the liquid crystal are aligned in some liquid crystal phases. Surface treatments in contact with the liquid crystal material may aid the alignment of the molecules of the liquid crystals. An example surface treatment is a thin film, such as a polyimide layer, formed on a surface of a substrate. The polyimide layer can be formed into an alignment layer for the liquid crystal by mechanically rubbing the polyimide layer in a single direction along the direction of alignment. Thus, the molecules of the liquid crystal material in contact with the polyimide layer may be aligned with the rubbing direction of the polyimide. However, rubbed polyimide has some potential disadvantages, such as surface defects, particle generation, and electrostatic charging. Alternatively, non-contact methods for producing an alignment layer may avoid some of the disadvantages of contact methods. Non-contact methods for aligning the molecules of the liquid crystal material include alignment using an atomic force microscope or an ion beam. However, these non-contact methods are impractical for large areas.